In recent years, with the rapid development of electronic technology, picture taking function of various devices is more and more powerful, which is not only more and more, and more and more powerful, such as: increasing image pixels, advancing the self-timer function, larger aperture, enhanced optical anti-shake function, accelerating the speed of focus, automatic focus, and various manually operating professional mode.
Many of the existing terminals, such as smart phones, are equipped with a picture taking device such as a camera. The picture taking device of many of the terminals has automatic focus function. Automatic focus is that when the target object is selected, the picture taking device can continue to focus on the target object, so that the target object in the output image remains clear. Even if the terminal with the picture taking device moves, the focusing area always includes the target object to achieve the goal of the automatic focus.
The picture taking device of some terminals supports automatic focus function, but when exposure changes, such as flashlight on or off, the automatic focus function suspends, so that user interaction increases and constant satisfactory images or videos will not be output.